This invention relates to a vehicle stability control apparatus which has a yaw moment control apparatus for optimizing vehicle stability to control wheel braking force of respective road wheels and has a traction control apparatus arranged to restrain a drive wheel slip at least by reducing engine torque.
As one example, Japanese Patent Kokai No. 9-286261 discloses a traction control apparatus that decreases the engine output power to restrain a driving wheel slip, by closing a second throttle valve operated by a DC motor and provided in series to a first accelerator connected with an accelerator pedal so that the opening degree of the first throttle valve is determined by the depression degree of the accelerator pedal, and by cutting off the fuel supply to one or more cylinders of the engine. Furthermore, if the driving wheel slip cannot be restrained by decreasing the engine output power, the traction control apparatus applies the brakes to the driving wheel.
This conventional apparatus is intended to decrease the engine output power to restrain the drive wheel slip in the first place, but if the wheel slip is not restrained by it, then the traction control apparatus applies the brakes to the drive wheel.
Such conventional traction control apparatus can have a selector switch to turn it on or off depending on the situation in which a traction wheel is stuck in a muddy place or the like.
As another example, Japanese Patent Kokai No. 9-2316 discloses a yaw moment control apparatus which makes the vehicle""s behavior more desirable by operating the braking force on the inside brake of the vehicle or on the outside brake of the vehicle during cornering.
It is an object of the present invention to provide a vehicle stability control apparatus and method which has a yaw moment control apparatus and has a traction control apparatus, which can prevent the traction road wheel from applying excessive braking force when the traction control apparatus is switched off.
According to one aspect of the present invention, there is provided a vehicle stability control apparatus which includes an engine and at least one drive wheel driven by the engine, the apparatus comprising: a wheel speed sensor to detect a wheel speed of the at least one driving wheel; an engine power control apparatus to control the engine output power in response to a first control signal; a braking force applying apparatus to apply braking force to at least the driving wheel in response to a second control signal; a vehicle behavior detector to detect vehicle behavior; a selectable switch to output an activation signal which places the engine power control apparatus in active state and an inhibition signal which place the engine power control apparatus in inactive state according to the selection by the driver; and a control unit operatively coupled with said wheel speed sensor, said engine power control apparatus, said braking force applying apparatus, said vehicle behavior detector, and selectable switch, wherein said control unit calculates a vehicle velocity from the wheel speed detected by the wheel speed sensor; the control unit calculates a slip of the at least one drive wheel in response to the wheel speed and the vehicle velocity; said control unit applies first control signal to said engine power control apparatus to decrease the engine output power according to the slip of the at least one drive wheel when said selectable switch is outputting the activation signal; said control unit applies the second control signal to said braking force applying apparatus to according to the vehicle behavior adjust the braking pressure to have the vehicle generate a moment in the stable direction; and said control unit applies said first control signal to the engine power control apparatus irrespective of a state of the selectable switch when the second control signal is applied to said the braking force applying a apparatus. According to the invention, the vehicle stability apparatus and method with an on-off-switch prevent the driving road wheel from applying excessive braking force when the traction control apparatus is off.
There is also provided a vehicle stability control apparatus which includes an engine and at least one driving wheel driven by the engine, the apparatus comprising: a slip sensor apparatus for detecting a slip of the driving wheel; a traction control apparatus for decreasing the engine output power according to the detected slip of the driving wheel; a selectable switch for switching the traction control apparatus on and off; a vehicle behavior detection apparatus for detecting vehicle behavior; a braking force applying apparatus for applying braking force to at least the driving wheel in response to a control signal; and a control unit operatively coupled with the vehicle behavior detection apparatus, wherein said control unit applies a control signal to adjust vehicle behavior to a determined value, and said control unit setting the traction control apparatus ON irrespective of a state of the selectable switch based on the control signal.
There is also provided a vehicle stability control apparatus which includes an engine and at least one driving wheel driven by the engine, the apparatus comprising: a slip sensor apparatus for detecting a slip of the driving wheel; a traction control apparatus for decreasing the engine output power according to the detected slip of the driving wheel; a selectable switch for switching the traction control apparatus on and off; a vehicle behavior detection apparatus for detecting vehicle behavior; a braking force applying apparatus for applying braking force to at least the driving wheel in response to a control signal; and a control unit operatively coupled with the vehicle behavior detection apparatus, wherein said control unit applies a control signal to adjust vehicle behavior to a determined value, and said control unit setting said selectable switch ON when adjusting the vehicle behavior based on the control signal.